Improved apparatus for grinding cutter-bits for rifling-machines



, UNITED STATES PATENT OFFICE.

DWIGHT SLATE, OF HARTFORD, CONNECTICUT.

IMPROVED APPARATUS FOR GRINDING CUTTER-BITS FOR RlFLlNG-MACHINES,

Specification forming part of Letters Patent No. 41,646, dated February 16, 1864.

being had to the accompanying drawings,

making part of this specification, and to the letters of reference marked thereon.

My invention relates to an apparatus for gi ving shape to the edges of the cutters which are used to rifle the barrels of fire arms.

Previous to my invention difculty has been experienced in giving to the edges of the teeth of riding-cutters the proper curvature for correctly shaping the bottoms of the grooves, and in rendering uniform the height and curvature of the edges of all the teeth where, as is usually the case, several cutters are used in the same rod, and each one cuts in all the grooves successively, in which case a slight variation in the height of the teeth causes an unequal action of the different cutters to an extent which is detrimental to the work.

It is the object of my invention to produce a tool by which the edges of the cutters7 teeth may be evened and properly curved while they are in their places in the riding-rod, or in a holder which has the precise form of the rod, and bywhich the several cutters may be rendered uniform in height and curvature.

To this end my said invention consists in the employment of a sleeve or equivalent guide so constructed that it may be applied to the riding-rod and rotated about the axis of the rod in combination with a slab of oil-stone or other similar abrading substance, which is so attached to the said sleeve that the rotation of the sleeve will cause the edges ofthe rilingcutters to be ground until they are of even height and perfectly concentric with the axis of the rod, substantially as hereinafter clearly described.

To enable others skilled in the arts to make and use my invention, I will proceed to a description thereof, referring to the accompanying drawings, in which Figure l represents a side elevation of the apparatus. Fig. 2 is an end elevation of the same. Fi g. 3 is alon gitudinal section of the tool7 shown in its application to a riflingrod, paits of which are also shown in section, and Fig. 4 is a cross-section of the same.

Similar letters denote the same parts in the several igures, whereina represents a long sleeve the bore of which iits the riding-rod for which the instrument is to be used 5 and b is a radial arm, which is secured to a at about midway of its length. o is a slab of oil-stone, which is fastened to the face of the arm b by means of the clamp d. The lower part ofthe oil-stone slab c enters a hole which is made through the side of the sleeve a, and it is so adjusted that its extreme lower end will (when the sleeve is rotated about its axis) describe a circle equal in diameter to that of the curve which is proper for the cutters teeth. The vcentral part of the bore of the sleeve a is enlarged, thereby forming a chamber two or three times longer than the riding-cutters. This chamber permits the protrusion of the cutters above the surface ofthe rifling-rod to which the sleeve may be applied. The end of the slab c enters the aforesaid chamber at the middle of its length.

In Figs. 3 and 4 there are shown parts of a riding-rod of the usual construction, in which s 'is the shell, r, the inner rod, which is of conical shape at m, where the three cutters n are supported.

Having described the construction of my invention, I will proceed to describe the mode of applying it. The cutters n of the riingrod having been dropped below the surface of the shell s, the sleeve a of the grinding apparatus is slipped onto the shell until the oilstone slab c is directly over the cutters, which are then thrust out by adjusting the cone m so far that the end of the slab c will rub on the edge of th at tooth of the cutterswhich may be the highest. The sleeve a is then rotated rapidly by rolling it between the hands, and the cutters must be gradually forced out until the abraiding action on the teeth by the piece of oilstone c has ground off the edges of all the teeth to an equal height and the proper curvature. This action of the oil-stone removes all nicks and inequalities of the edges of the teeth and leaves them perfectly smooth, and in such shape that they may readily be sharpened in the usual way. When the end of the l by loosening the eizunp d and "resetting the slab. y.

The slab c may be made of any material sleeve a, or their respective equivalents, eonstructed, arranged, and operating substantiztlly in the manner hereinbefore set forth.

In testimony whereof I have hereunto set which has an abradingsurface capable of my hand this 18th day of August, 1863.

grinding away the edges of the hardened out ters Without crumbling them.

What I ela-im as my invention, and desire to secure by Letters Patent, is-

Ihe oil'stone slab c, in com binzttion with the DWIGHT SLATE.

In presence of- FRANCIS FELLOWES, FRANoIs FELLOWES, Jr. 

